Glow-in-the-dark watches are cool. Early in the twentieth century, the luminous hands and numbers on watches were often hand-painted by young women in fac- tories. In order to keep their brushes sharp for the fine work, they would often lick the brush, thereby ingesting small quantities of radioactive radium. This sim- ple act had tragic consequences. Ingested radium destroyed bone tissue. In some cases, women lost their jaws and, worse, their lives. Draw a graph to illustrate this externality associated with radium-painted watches